1. Field of the Invention
The present invention relates to a television/cinema scheme identification apparatus and identification method capable of precisely identifying whether a video signal image has been acquired by means of a general video camera or a picture of a cinema film has been converted into the video signal image.
2. Description of the Related Art
In recent years, there have been a picture of a cinema film, a picture caused by computer graphics (hereinafter, referred to as a CG), and a picture acquired as an image by means of a general video camera as sources of the video signal image. Thus, a television broadcast signal in an NTSC scheme or a PAL scheme and a video disk reproduction signal often include a cinema film image signal or a video signal caused by the CG. In addition, in recent years, there has been a case in which picture signals of a variety of sources coexist with an increased recording capacity of a recording medium (for example, a DVD (digital versatile disk) or a hard disk) and digitization of a transmission scheme.
A cinema film has 24 frames per second; an NTSC standard television signal is provided as a picture signal for interlace scanning in 60 fields per second; and a PAL standard television signal is provided as a picture signal for interlace scanning in 50 fields per second. Therefore, a picture of a cinema film and a CG picture are subjected to television/cinema conversion, and the converted images are produced as an NTSC television signal or a PAL television signal.
As the television/cinema scheme, a 2-3 pull-down scheme and a 2-2 pull-down scheme are known. The 2-3 pull-down scheme is provided as a scheme utilized when a cinema film of 24 frames per second is converted into an NTSC television signal. In this scheme, 2 frames are divided into 5 fields, and 2 or 3 fields produced from an identical frame are designated by identical alphabetical letters. If a numeric value is subscribed with respect to a time series, it is designated by a 5-field sequence like A1, A2, B1, B2, B3, C1, C2, D1, D2, D3 or the like.
On the other hand, the 2-2 pull-down scheme is provided as a scheme which can be utilized when a CG picture is converted into an NTSC television signal. 1 frame is divided into 2 fields, and 2 fields produced from an identical frame are designated by identical alphabetical letters. If a numeric value is subscribed with respect to a time series, it is designated by a 2-field sequence like A1, A2, B1, B2, C1, C2, D1, D2 and the like. Further, the 2-2 pull-down scheme, for example, is adopted when a film picture of 24 frame per second is converted roughly into a video signal of 50 Hz (50 fields per second).
On the other hand, to respond to a user's demand, a scanning line conversion processing apparatus for converting an interlace signal into a non-interlace or a progressive signal has become available for a video signal processing section in recent years so as to produce a high quality and wide screen display image.
In the meantime, in the case of carrying out scanning line conversion processing, it is necessary to identify a source of the above-described video signal. This is because, after two fields composed of interlace signals has been subjected to line interpolation in a superimposed manner, when the interlaced signals are converted into non-interlace signals, if the two fields to be used are not fields from an identical source (a same frame), the quality of the acquired image is degraded.
Conventionally, a number of proposals have been made as a television/cinema scheme identification apparatus for identifying a source of a pulled-down video signal.
In particular, there has been a technique for achieving identification of a 2-3 pulled-down video signal and identification of a 2-2 pulled-down video signal by a single apparatus. This technique is disclosed in an embodiment of Jpn. Pat. Appln. KOKAI Publication No. 9-18784. In this embodiment, with attention being paid to a vertical synchronizing frequency of an input video signal, when a field frequency is 60 Hz, a 2-3 pull-down scheme identification circuit is operated, and when a field frequency is 50 Hz, a 2-2 pull-down scheme identification circuit is operated. Thus, in the case where an NTSC signal having a vertical synchronizing frequency of 60 Hz is a 2-2 pulled-down video signal, it is difficult to make identification.
In addition, as another prior art, there is a technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2003-78926. In this art, identification between a 2-3 pulled-down video signal and a 2-2 pulled-down video signal are individually carried out by utilizing a property of a video signal itself. Thus, this technique may cause a problem from the practical point of view.
The 2-3 pulled-down video signal is identified by computing a difference between frames with respect to an input video signal. The 2-2 pulled-down video signal is identified by computing a difference between fields. Therefore, it is easily predicted that a majority of identification schemes of both of these systems have different circuit constructions, and that identification sensitivities between the identification schemes of both of the systems are different from each other. In addition, it is expected that there will be a trouble in adjustment for identifying the sensitivities of identification schemes of both of these systems. Further, there is a danger as to whether or not there exists a case in which results obtained from these 2 identification schemes compete with each other with respect to the same input video signal. Identification for a video signal in the 2-2 pull-down scheme can be carried out in a small number of field intervals, and is carried out prior to identification for a video signal in the 2-3 pull-down scheme. Therefore, it is not possible to overcome a question as to whether or not a deviation of identification sensitivities occurs.
Further, as another prior art, there is a technique disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2002-330311. In this technique, there is provided a construction such that identification of a picture source is made by comparing 6 pixels, for example, in a coordinate block in which a picture signal in a current field is equal to a picture signal before 2 fields, so as to form hysteresis with respect to identification due to a change of a threshold value during this identification.
However, as described above, in the prior art, identification of a 2-3 pull-down video signal, a 2-2 pull-down video signal, and a general video signal merely proves its feasibility, and has a number of problems at a practical level. In addition, even if the identification sensitivity can be increased to an extent such that it reaches a practical level, there is a trouble with making such adjustment, leading to an increase of an adjustment period up to shipment of a picture processing product and causing high cost of a picture processing product. Additionally, no countermeasure is taken against an incorrect identification inducting picture pattern which may cause due to a picture pattern, and a danger of incorrect identification cannot be eliminated on a practical level.
Currently, there are many cases in which a picture element is produced by using a computer graphics composing technique (hereinafter, referred to as a CG composing technique). The CG has an advantage in picture production in that an unrealistic picture can be produced and in that a restriction on a location site or period can be reduced. Such a picture produced by combining the CG is considered to increase in the future. In the GC, it is general that a non-interlace image is handled. In Japan employing an NTSC standard, a picture of 30 frames per second is produced in consideration of affinity with a television broadcast. In the case where this image is converted into an NTSC standard television signal, such conversion is made in accordance with the 2-2 pull-down scheme.
Further, a recent video signal source includes a source in which various types of pull-down video signals coexist. A DVD is an typical example of recording such a source. The DVD includes a so-called “making picture” recollecting a pattern during cinema or video clip imaging. A scene of interview with an actor or a singer is imaged in a general video image, and scenes inserted as recollection scenes of the actor or singer are produced in 24 frames in the case of cinema imaging and in 30 frames in the case of CG. A number of video signals are edited in an arrangement in which these scenes are switched intentionally within a short period of time.
Moreover, in a DVD cinema as well, because a title indicative of the beginning of a cinema is made up of a 30-frame CG and because a 2-2 pulled-down video signal and the context of the DVD cinema have been imaged in 24 frames, there exists a DVD having recorded therein a 2-3 pulled-down video signal as well.